Medicare Open Enrollment: 7 Costly Mistakes to Avoid When Changing Your Plan

Medicare open enrollment, officially called the Annual Election Period, runs from October 15 through December 7 every year. During this window, you can switch from Original Medicare to Medicare Advantage, switch between Medicare Advantage plans, return from Medicare Advantage to Original Medicare, or join, switch, or drop a Part D prescription drug plan. Changes take effect on January 1 of the following year. The reason this matters every year is that plans change their benefits, costs, formularies, and provider networks annually. The plan that was the best value for you last year might not be the best choice next year, and staying on autopilot can cost you hundreds or even thousands of dollars.

The most common and most expensive mistake is simply not reviewing your current plan during open enrollment. Every fall, your plan sends you an Annual Notice of Change that lists all the modifications to your benefits, premiums, copayments, and drug formulary for the coming year. Many people throw this notice away without reading it. A drug that was on your plan's formulary this year might be moved to a higher cost tier or removed entirely next year. Your monthly premium might increase by $20 or $30. A specialist you see regularly might leave the plan's network. Any of these changes could make your current plan significantly more expensive or less useful, and you would not know unless you read the notice and compare your options.

Set aside 30 minutes each October to review your Annual Notice of Change and compare your current plan against other available plans using the Medicare Plan Finder tool at Medicare.gov. Enter your medications, doctors, and pharmacy to see estimated annual costs under each plan. This simple exercise consistently saves people hundreds of dollars per year. If you find a better plan, switching during open enrollment is straightforward and free. If your current plan still provides the best value, you can stay enrolled with confidence rather than wondering if you are overpaying.

A $0 premium plan sounds like a great deal, and for some people it genuinely is. But focusing only on the monthly premium without considering the full cost picture is like choosing a restaurant based only on the price of the appetizers. Your total annual cost includes the premium, the deductible, copayments for doctor visits and procedures, coinsurance for hospital stays, and out of pocket drug costs. A plan with a $35 monthly premium but $20 primary care copays and a $250 drug deductible might cost less overall than a $0 premium plan with $30 primary care copays and a $545 drug deductible, especially if you visit the doctor frequently or take multiple medications.

Drug formularies change every year, and a medication that was covered at a low copay this year could be moved to a higher tier, subjected to prior authorization, or dropped from the formulary entirely next year. If you take any medications regularly, checking the formulary of your current plan and any plans you are considering is essential. The Medicare Plan Finder lets you enter your specific medications and compare the annual drug cost across all available plans. A difference of $500 to $1,000 in annual drug costs between plans is not unusual, particularly for beneficiaries who take brand name or specialty medications.

If a medication you rely on is no longer covered by your plan, you have the right to request a formulary exception, asking the plan to cover the drug at a lower tier or without prior authorization. Plans are required to have an exceptions process, and exceptions are sometimes granted when the prescribing doctor provides clinical justification. However, this process takes time and is not guaranteed to succeed, so switching to a plan that covers your medications without requiring an exception is often the more reliable solution.

Medicare rates every Medicare Advantage and Part D plan on a scale of one to five stars based on quality measures including customer satisfaction, health outcomes, and how well the plan helps members manage chronic conditions. Plans rated four stars or higher are considered above average, and there is a real correlation between star ratings and member experience. Higher rated plans tend to have better customer service, fewer claim denials, more responsive grievance processes, and better coordination of care. When comparing plans with similar costs and benefits, the star rating is a meaningful tiebreaker that reflects the quality of the experience you can expect as a member.

The open enrollment window closes on December 7, and there is no grace period. If you miss the deadline, you are generally locked into your current coverage for the entire following year. There is a limited Medicare Advantage Open Enrollment Period from January 1 through March 31 that allows you to switch from one Medicare Advantage plan to another or return to Original Medicare, but this window does not allow you to move from Original Medicare to Medicare Advantage or to join a standalone Part D plan. Mark the October 15 start date on your calendar and begin your review early. Do not wait until the first week of December to start comparing plans because you may need time to research providers, check drug coverage, and make phone calls to clarify plan details.

If comparing plans feels overwhelming, free help is available. Every state has a State Health Insurance Assistance Program, known as SHIP, that provides free, unbiased Medicare counseling. SHIP counselors are trained volunteers and staff who can help you compare plans, understand your benefits, and make enrollment decisions. They do not sell insurance and have no financial incentive to steer you toward any particular plan, which makes their advice more objective than what you might receive from an insurance agent or broker who earns commissions on the plans they sell.

Medicare.gov's Plan Finder tool is the most comprehensive resource for comparing plans because it includes every plan available in your area with accurate, up to date cost information. You can also call 1 800 MEDICARE for help navigating the comparison process. Local Area Agencies on Aging, senior centers, and community organizations often host enrollment events during the open enrollment period where counselors are available to help you review your options in person. Take advantage of these free resources rather than making a decision based on a television advertisement or a mailer from an insurance company. The stakes are too high and the potential savings too significant to leave your coverage choice to chance.